Operator overload +

can someone please help me on operator overloading +
I have supplied the main file and the implementation file. I am writing an application that records the items (books) sold and calculates/displays the totals (costprice and sellprice) and the average total sales for each day. i'm not getting the results i'm expecting. The problem is in the operator overload :
The out-put should be something like this:

report for monday, march 02, 2004
Total Sales: $180
Total Cost: $150
Average: $15.00
report for tues...etc.,
In my main class i record the sales like this and then call the copy constructor: